Left-handed color-sextet diquark in the kaon system

Chuan Hung Chen, Takaaki Nomura

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We investigate whether a color-sextet scalar diquark (H6) coupling to the left-handed quarks contributes to the ΔS=2 process. It is found that the box diagrams mediated by W and H6 bosons have no contributions to ΔS=2 when the limit of mt=0 is used, and the flavor mixing matrices for diagonalizing quark mass matrices are introduced at the same time. When the heavy top-quark mass effects are taken into account, it is found that in addition to the W-H6 box diagrams significantly contributing to ΔS=2, their effects can be as large as those from the H6-H6 box diagrams. Using the parameters that are constrained by the K0-K̄0 mixing parameter ΔMK and the kaon indirect CP violation ϵK, we find that the left-handed color-sextet diquark can lead to the kaon direct CP violation being Re(ϵ′/ϵ)∼0.3×10-3. In the chosen scheme, although the diquark contribution to KL→π0νν is small, the branching ratio of K+→π+νν can reach the current experimental upper bound.

Original languageEnglish
Article number115006
JournalPhysical Review D
Issue number11
Publication statusPublished - 2019 Jun 6


All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

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